What causes mitral valve prolapse?

Mitral valve prolapse (MVP) is among the most common heart conditions; however it remains something of a puzzle. Although MVP affects about two percent of the population, the cause is unknown. MVP often occurs in people who have no other heart problems, and the condition may be inherited.

The mitral valve is located in the heart between the upper-left chamber (the left atrium) and the lower-left chamber (the left ventricle). The mitral valve consists of two flaps called leaflets.

In normal operation the leaflets open and close in a specific sequence. This allows the blood to flow in one direction, from the atrium to the ventricle. The left ventricle is the heart’s main pumping chamber and pushes oxygen-rich blood into the arteries, which carry the blood throughout the body.

In patients with MVP, one or both of the leaflets are enlarged, and the leaflets’ supporting muscles are too long. Instead of closing evenly, one or both of the leaflets collapse or bulge into the atrium sometimes allowing small amounts of blood to flow back into the atrium. By listening to the heart with a stethoscope, the doctor may hear a “clicking” sound caused by the flapping of the leaflets.

Sometimes, MVP leads to a condition known as mitral regurgitation or mitral insufficiency. This means a large amount of blood is leaking backward through the defective valve. Mitral regurgitation can lead to the thickening or enlargement of the heart wall. This is caused by the extra pumping the heart must do to make up for the backflow of blood. It sometimes causes people to feel tired or short of breath. Mitral regurgitation can usually be treated with medicines, and some people need surgery to repair or replace the defective valve.

Most of the time, MVP is not a serious condition, even when some patients report palpitations or sharp chest pains. Most patients do not need treatment